1. Technical Field
The present invention relates to an input device which has an illumination function and a keyboard device in which contacts contact with each other by a plurality of key tops, and particularly, to a keyboard device having a function of illuminating a key top.
2. Related Art
Personal computers or various information searching apparatuses are equipped with a keyboard device in which a plurality of key tops are arranged.
In recent years, the keyboard device has been required to have an illumination function of allowing a user to recognize key tops in a dark place. Particularly, book-type or laptop-type personal computers have been required to be equipped with an input device and a keyboard device having an illumination function so as to visually recognize the key tops in a dark place.
In a keyboard device disclosed in Japanese Patent Application Laid-open No. 2002-251937, an electroluminescent element is disposed on the rear side of a base substrate supporting key tops, and light emitted from the electroluminescent element is applied to the key tops through perforation holes formed in the base substrate.
In a keyboard device disclosed in Japanese Registered Utility Model No. 3082585, a plate-shaped light emitting element including a cold-light plate or a cold-cathode plate is formed on a base, a circuit board and an elastic sheet are laminated on the light emitting element, and then a plurality of key tops is formed on the elastic sheet. Light emitted from the plate-shaped light emitting element is applied to the key tops through holes formed in the circuit board and the elastic sheet.
In the keyboard device disclosed in Japanese Patent Application Laid-open No. 2002-251937, the electroluminescent element is disposed on the rear side of the base substrate, and the light is applied to the key tops through the perforation holes opened to the base substrate. Further, in the keyboard device disclosed in Japanese Registered Utility Model No. 3082585, the light emitted from the plate-shape light emitting element is applied to the key tops through the holes formed in the circuit board and the elastic sheet.
Likewise, since the known keyboard devices have a structure in which the light emitted from the light source is applied to the key tops through the holes formed in other members located above the light source, the utilization efficiency of the light used for illuminating the key tops is not satisfactory. In addition, since the light is interrupted by the base substrate or the like interposed between the key top and the light source, it is difficult to uniformly illuminate the key tops.
Further, in the keyboard devices disclosed in Japanese Patent Application Laid-open No. 2002-251937 and Japanese Registered Utility Model No. 3082585, since the sheet-shaped light source is used, it is not possible to intensively apply the light to an illumination target position of the key top.
These and other drawbacks exist.